Method and apparatus for the production of shale oil from oil shale



A. .1. JOHNSON ET AL 2,694,037 METHOD AND APPARATUS FOR THE PRODUCTION rOE sHALE OIL FROM O11. sHALE 7 Sheets-Sheet l v Nov. 9, 1954 Filed April '7, 1950 w CNN GEORGE E. LIEDHOLM MAL-DEN C. LOWMN BY dma-r/ WM HEIR ATTORNEY Nov. 9, 1954 Filed April '7, 1950 oHNsoN ET AL 2,694,037

7 Sheets-SheetI 2 Flgln lnvzhi'ors: Ava J. Johnson Geox-gz E. Lied hdm l MoldqnCLowmon EN" Mw/HHM Their A''fornzg A. J. JOHNSON ETAL T 2,694,037 METHOD AND APPARATUS POR THE PRODUCTION OF SHALE OIL FROM OIL SHALE 7 Sheets-Sheet 5 .F ...v m s@ Orgon Nov. 9, 1954 Filed April 7, 1950 INVENTORS AVA J.' JOHNSON 6:01265 E. LnzDHoLm MLDELN C. LOWMAN BY: m ddh/m THEIR ATTORNLY Nov. 9, 1954 A. J. JOHNSON ET AL METHOD AND APPARATUS FOR THE PRODUCTION OF SHALE OIL FROM OIL SHALE Filed April '7, 1950 '7 Sheets-Sheet 4 Mcdzn C. Lowman Bly 'The (r ATTOrrvLg Nov. 9, 1954 A. J. JOHNSON ET AL METHOD AND APPARATUS FOR THE PRODUCTION OF SHALE OIL FROM OIL SHALE Filed April 7, 1950 7 SheeiEs-Sheet 5 INVENTORSI AVA J. JOHNSON GEORGE E.. LIEDHOLM MALDEN C. LOWMAN THEIR ATTORNEY FIG. III

7 Sheets-Sheet 6 PREHEATER EXCHANGER FRESH SHALE J. JOHNSON ETAL PARATUS FOR THE PRODUCTION ,TxfwvLfwfL A. METHOD AND AP OF SHALE OIL FROM OIL SHALE RETO RT F IZESH SHALE INVENTORS'.

AVA J. JOHNSON GEORGE. E. LIEDHOLM MALDEN C.' LOWMAN BY: maa/MM T EIR ATTORNEY mnlllllllr FIGJ FGJY

Nov. 9, 1954 Filed April 7, 195o iw L RETOIZTING ZONE\ PREHEATER ExcHANGER Nov. 9, 1954 A. J. JOHNSON ET AL METHOD AND APPARATUS FOR THE PRODUCTION OF SHALE OIL FROM OIL SHALE 7 Sheets-Sheet Filed April '7, 195o PM OFM N INVENTORS: AVA J. JOHNSON GEORGE. E. LIEDHOLM MALDEN C. LOWMAN BY: I l

/ HEIR ATTORNEY United States Patent O METHOD AND APPARATUS FOR THE PRODUC- TION OF SHALE OIL FROM OIL SHALE Ava J. Johnson, Oakland, George E. Liedholm, Berkeley, and Malden C. Lowman, San Rafael, Calif., assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application April 7, 1950, Serial No. 154,482 11 Claims. (Cl. 196-S6) bearing materials, particularly to recover oil from oilshales. In one of the methods presently receiving commercial consideration for the recovery of oil from oilbearing material, oil shale is retorted in such a manner as to maintain a stationary zone of combustion near the top of an oil shale layer and at the same time moving fresh shale upwardly into this zone of combustion and drawing the products of combustion downward, countercurrently to the upward moving fresh shale, so as to preheat the latter and at the same time to drive off the petroleum oils and also to effect cooling and/or condensation of vaporized oil. In producing oil by this method it is necessary to introduce large quantities of air. As a result the product gases, containing the vaporized oils, are diluted with a large amount of inert nitrogen thereby decreasing the B. t. u. content of the product-combustion gas and also rendering the recovery of the C3 and C4 hydrocarbon gases therein very diicult. Various other retorting methods have also been suggested but so far none of the methods proposed have been entirely satisfactory.

The principal object of the present invention is to provide a method for recovering available petroleum oil from oil-bearing solid substances, and particularly, from oil shales. A more specific object of the invention is to recover petroleum oil from oil shale by the use of hot combustion gases arising from the combustion of previously extracted shale. Another object of the present invention is to provide a continuous method for recovering shale oil from oil shale and the like in a system generally operated at elevated temperatures in which the heat necessary to maintain the system in operation is obtained by burning materials within the system. Other objects of the invention will appear in the following more detailed description of the invention.

Now, a process has been discovered by which oil may -l'v be readily and efficiently recovered from oil-bearing materials, lsuch as oil shales and other related materials. This process overcomes the inherent difficulties present in processes previously employed for the removal and recovery of oils from oil shales and the like and at the same time permits a maximum recovery of the oil in an efficient manner.

In accordance with the present invention, oil-bearing material, especially oil shales, are crushed, preheated by certain hot end-products of the process, as will be .described, and then transferred to a retorting zone wherein the shale is passed downwardly countercurrently to hot gases so as to separate the oil from said oil-bearing material. At least a portion of the resulting oil in a vaporous state is then handled in a manner as to effect maximum heat economy consistent with efficient product recovery and quality.

A feature of one embodiment of the invention is to crack at least a portion of the recovered shale oil by oxidative cracking and to employ the heat thereby generated in the oil-recovery operation. In accordance with this embodiment of the invention crushed oil shale is countercurrently contacted with the gaseous product from a cracking reactor so as to preheat the oil shale,

thereafter the oil shale is passed countercurrently to hot so More particularly, the invention is con-- 2,694,037 Patented Nov. 9, 1954 gases within a retort so' that shale oil is driven off from the oil shale and vaporized by these hot gases. Thereupon said vaporized shale oil is quenched by contact with a heavy shale oil fraction obtained by condensing and recovering a portion of the product vapors of said cracking reactor from said crushed oil shale and the resulting admixture in intimate mixture with oxygen is passed into said cracking reactor wherein oxidative cracking is carried out.

A feature of another embodiment of the invention is to crack at least a portion of the recovered shale oil by contact coking instead of oxidative cracking, in such a manner that hot spent shale provides the contact surface as well as a substantial portion of the heat required for coking. Thus, in accordance with this embodiment of the invention, crushed oil shale is countercurrently contacted with gaseous shale oil so as to preheat the oil shale and condense said shale oil, thereafter the oil shale is passed countercurrently to the hot gases within a retort so that shale oil is driven from the oil shale by these hot gases. Thereupon said shale oil is fractionated so as to produce light fractions which are drawn olf as product and a heavy bottoms fraction which is then passed to a contact coking zone wherein it is contacted with hot spent shale and the heavy components of said bottoms fraction are thermally decomposed with the formation of a coke and lower molecular Weight components. The shale oil vapors from the coking zone are commingled with the shale oil vapors from the retort- `ing zone and the above-described fractionation step carried out again in such a manner as to maintain a continuous process.

, The invention will be more lfully understood from the following detailed description thereof made with reference to the drawings: Figure I of which is a diagrammatic representation of the process employing oxidative cracking; Figure Ia of which is a diagrammatic representation of a modification of the method as illustrated in Figure I; Figure Ib of which is a diagrammatic representation of a second modification of the method as illustrated in Figure I; Figure II of which is a diagrammatic representation of the process employing contact coking; Figure Ila of which is a diagrammatic representation of a modification of the method as illustrated in Figure II; Figure IIb of which is a diagrammatic representation of a second modfication of the method as illustrated in Figure II; Figure III of which is a diagrammatic representation of the process employing applicants preferred method of contact coking; Figure IV of which is a diagrammatic representation of a method of preheating and retorting oil shale; Figure V of which is a diagrammatic representation of a modification of the method as illustrated by Figure IV and Figure VI of which is a diagrammatic representation of applicants preferred method of preheating and retorting oil shale as illustrated by Figures IV and V.

Figure I shows diagrammatically an apparatus layout in which a preferred modification of the invention may be carried into effect.

Referring to Figure I, oil shale such as is found in vast quantities in the United States, particularly in Colorado, containing, for example, about 30 gallons of shale oil per ton, by Fischer assay test, after being crushed to an average size of about one inch is fed from fresh oil shale hopper 11 into an elevator-exchanger 12. The elevatorexchanger is shown as a long, upright or inclined structure. Althoughit may have many forms, as will be well understood, it is preferably a bucket-type elevator with perforated bottoms in the buckets. An alternative would be to use a reciprocating feeder device such as is shown in the drawing at 14. The fresh crushed oil shale is moved upward within the elevator-exchanger and transferred by suitable means 15, such as a screw conveyor, to retort 16. The retort may be a large upright vessel, lined with firebrick and containing distributing means 17 in the upper section near the top so as to evenly distribute the fresh incoming oil shale from the elevatorexchanger. In the lower section of the'retort is located a zone of combustion maintained by a supply of oxygen from line 19 and introduced and distributed therein by means'20. -Close 'to 'this zone of combustion and di- Irectly lbeneath -it Ais located means -21 `for -introducin g1 and distributing the water used; to cool the hot spent shale coming from the zone of combustion and thereby supply the steamsrequiredor fthe rprocesszand control of'v .the --volume percentage;of oxygen'infthezonecf combustion. .'rstillfurther, close to .meanssZlfis -means-..22 Whichwmay .:beranyf vof thef many. vstandard. devices,: suchwas shaking rgrates, :to permit the cooledl spent,` shale: .tor -zbe-.qdropped from'zthel retort. Asis Vobvious from thefabovetarrangezzmentgithe: fresh.V shale, evenly distributed'fwithinn the; re-

tort, moves downwarduniformly 'under'..theforce-of gravity as the spent shale is ejectedzfromfthe 4fretortl :Thef steam, formed` when water introduced by means 21 ."todirectlyv quench-and cool thehot spent shale coming fzfromzthe combustion zone,'is Vsuperheated as'it=passesfon vup through .the bot-.combustion '.zoneg'tthus, thee-super- ;heated steamzand 4thexhot combustion .gasesmoving ,up- Vvwardly i-withinthe fretortandv countercurrently .torthe Aoil fshale, serve to supply the heat necessaryto:drive oi the `:oil from the` oil. shale.

The vaporized. shale =oil, sweptalong with fthe .-steam rand.V combustion. gases, leaves the. retort-by;line23 to:a -quench tower 24 wherein the -vaporized.. shale i oil. is :.quenched'and cooled in order .to lower :its-temperature 'below the threshold -temperatureV-above--whieh srapid, excessive combustiony would take.;place in. subsequent -oxidative cracking :reactor 25. The quenching .is-.ac-

complished by. a liquid, unconverted, :heavy oiltraction obtained from theelevator-exchangerlas aside cut'via v:line 26 and stripper 27 whichis Vsupplied with ay suitable lstripping agent; such -as steam, .hot product gases, -etc., to .removeythe' light fractions. fromsaid .heavy -oilxfracations fromv whence it is -led by line. 29 intoA the-upper -section =of the quench =tower. Valved line :.28,-which may lead to product separator 41, is a drawogfrom line 29 so thatthe amountofheavy=oilfused for quench- .ing may be varied. t-The. cooled `overhead'vaporfrom the quenchtower is led by line' 30 and the liquid bottoms of thequench towerare-led by :line 31to l.blower-mixer (eductor) 32vwhere. aminor amount (from l yto..20% :by-volume) .fof-oxygen isadded Vand mixed therewith, from line 34,and the 'mixture `them-blown fthroughflineSS into the refractory-lined;cracking reaotor'25, an upright, unpacked reactionv chamber whereinvoxidative cracking .,occurs. Dry granulated. coke `which is producedwand accumulates therein may' be..taken from,.therreactor by means of line 36. The gaseous products from thefcracking reactor are thenled byline 37` tosthe upperiportion of the elevator-exchanger where..they .arecooled and condensed by the fresh .incoming shale. This theatexchange servesalso. to preheatthefresh shale.

The heavy -unconverted oil used .in the..quench.tower shouldpreferably'have an initial boilingpoint ofratleast v about.200C. It is readily seen, however, from Athe preceding descriptionthat.the1.amount.;and,.proper.ties .of 4this quench oil yare dependent.uponthe..location from .which it is withdrawn from..the elevator-exchanger -via ..line`26 and stripper'. 27, i.v e.,. more oil and. containinga greater proportion of-lowerboiling materiall'ifdesired) will be obtained ifthe quench oil isremovedtrom a lower section of the .elevator-exchanger Athan from .a `Vhigher section. Also the temperaturegof, the .quench oil when removed from a higher section .of the Aelevatorexchanger xwill-be greater than the ...temperature of. oil removed from the 'lower'section "Thus, the amount. of quenching oil `required to bring its ,gaseous .admixture *with the-gases 'emanating'.from the retort toa tempera- *ture below the threshold temperature desired`forV they 'oxidative cracking will vary according tofthe operating vvconditions of the process. Y

' Furthermore, it may be desirable4 tok employanumber of strippers, such as -stripper`27, thereby ,effecting a separation of the shale oil being condensed within the elevator-exchanger yinto -various fractions having the boiling point lrange desired andr eliminating orgreatly lreducing the need for a fractionatorftto separate` productlfractions from the liquid shale yoil collectedA in product separator 41.

-'The s condensed product'from exchanger 12 is led by l:lines-39fand14t) to line 43 to separator-41, the uncon- 'densed product gasesbeing removed therefrom by line 42, .the condensed liquid oil product being removed by line f44andi an aqueous layer being removed by line 45, yfrotar-Which. itlis` deliveredfbyf-means of pump 46A and Voccur .in-.retorting Aprocesses 'wherein .tionimay also be more ."hydrocarbon gases.

y product but i d more coordinated operation'for the recovery of amline 47 to distributing means 21 in the lower section of -the'retort -toV supply Athe steam required 1tor -the process.

It is pointed out that a condenser (not shown) supplied with a suitable coolant (shale oil product, water, air, 5 etc.) may be placed between line 43 and separator 41 to recover uncondensed water and shale oil product emanating from the elevator-exchanger. Also make-up wvater, to'replace any losses, may be added to the process by line 48 connecting with line 45.

.it will be noted that in thegabove description of the j process the. oil shale moves evenly downwardly within 'the retort. countercurrently to the hot combustion gases and superheated steam emanating from the zone of combustion. By permitting the oil shale to descend within l5 the retortunder 4the linuence of gravity as the spent shale is removed an even solids ow is thereby achieved. This avoids theformation of stagnant layers of shale which tend to form around the walls of the retort causring channeling ofltheoilshale and gas ows Which-could a zone'of combustiontinthe upperesection of'theretorting zone is `fed -iby van upwardimovingbody of. oil shale.

Oxygen Vof approximately 95% purity, such asmaybe -readilyobtainedby thefractionation'of air, isemployed Ziato maintain the'zone of combustion in the lowersection :of v;the;tretort. 'Itz is"realize`dthat oxygen-enriched air -or air mayalsobe'used but approximately pure oxygen ispreferable. Byernploying oxygen it is possible'. to carry-soutien efticientxcombustion of the spent shale BOiafterntthe'volatile :hydrocarbon components have been Adriven.oifsince'the spent lsliale still contains from about 2%"to about5%4 by weight carbon. At the same time 'fbyz controlling the amount of oxygen being admitted to :the retort theextentand depth of the zone or" combusaccurately controlled. #Another advantagexgained byemploying oxygen in- 's steadzof'air.. is that the 4light hydrocarbon gases, such as ICs and .C4'hydrocarbons, driven oi from the oil shale within zthe. retortare. not diluted with. large quantities 4010i nitrogen .so asto'render ythe separationof those light hydrocarbon gases difficult, impractical or uneconomical. yFurthermore, since nitrogen is not present as a diluent, '..theheat'conlentper unit of mass or volume of the gases emerging from the retort is greatly increased.

In the retort the water which is recycled and recovered '.from 'the-.products -as' an aqueous layer in the separator is employed: notonly as ameans of quenching and cooling: thehot `spent shale from the zone of combustion' to about250 F. but also, because of its high specitic heat,

5Ui'it is: anweicientvand excellent heating-medium for use linzthe'retorting section of the retort. In a sense, steam -replaces nitrogen as a diluent if air instead of oxygen r.wereleniployedin the retort but to the great advantage ."that;steam:.rnay be readily separated from the light Also, because of the high latent :heatofrvaporization of water and the high speciiic heat of water vapor,.thewater serves to take up and/ or supply aportiontof the heat required for cooling and heating the shale. Furthermore, because of the high specific "iheat-"and'latentfheat of vaporization of water it is possible 'to-maintain a relatively low total mass ilow through the systemes-.compared with a similar system not employing :water while at the-same time allowing for discharge oi w spent `shale ata reasonably low temperature.

d Another advantage-gained by the use of steam is that the-#maximum temperatures in the retort may be controlled thereby avoiding overheating andcalcination of 'zthe oilshale. `This is advantageous because calcination ".of'the'carbonates in the fresh shale not only uses upk a "PU largeV amount ofl heat but also results in dilution of the hydrocarbon'gases withl carbon dioxide.

`Stillanother advantage is that the use of steam not onlyresults in a lower nitrogen content in the gaseous also offers the possibility of a simpler and v-rnonia' as a -by-productof the shale oil.

For the reasons pointed out above,.it is important to-avoid excessive temperatures in the retorting section `of the'retort,A i. e., that section `wherein the volatile S0petroleum components are removed from the oil shale by the action of the hotgases and superheated steam. yAsuit'able maximum temperature in the retorting zone is vabout 1200" F. `Above this temperature calcination of the'carbonates contained in the oil shale tends to become excessive An'operating temperature` of about- 9GO1G0O `sirab1e, it is probable that ,a bed of spent shale P. in the retorting section with an oil shale residence time therein of about 2 hours is most suitable and preferable. However, as is obvious from the above discussion the operating conditions may be widely varied, dependent upon equipment, size of shale particles, richness of oil shale, etc.

The location of the quench tower -or any other suitable liquid gas contacting device such as a mixing valve, etc., between the retort and the cracking reactor is most appropriate and advantageous. Not only are the hydrocarbon vapors, steam andcombustion gases emerging from the retort cooled by direct contact with recycled heavy product obtained as a side cut from the elevatorexchanger in order to bring the feed to the oxidative cracking reactor below the threshold temperature above which rapid, excessive combustion would take place but it also serves as a particularly desirable and advantageous method and point for the introduction of recycle heavyy oil to complete the cracking of this unconverted heavy oil. The threshold temperature below which it is desirable to cool the hydrocarbon vapors before oxidative cracking is in the neighborhood of 750 F.

Circulation of the gases through the process may be suitably obtained by means of a blower-mixer. The blower-mixer serves not only to educt the gases from the retort through the quench tower and then to blow them into the cracking reactor wherein the oxidative cracking is effected, but it also serves as an effective mixing device at the point of introduction of the oxygen into the feed for the reactor. An intimate andy uniform feed mixture is necessary for successful and efficient operation of the oxidative cracking step carried out in the cracking reactor. The operating temperature of the cracking reactor should be carefully controlled since too high a temperature would cause excessive oxidation, resulting in low product yield and excessive formation of coke. It is preferred to operate the cracking reactor at a temperature in the range 650-l000 F., preferably about 950 F.

The oxidative cracking process is used to great advantage in this process since it serves to reduce the heating and the cooling requirements of the process. The latter is especially important because of the isolated location of oil-shale deposits away from large supplies of water. In addition, by utilizing the oxidative cracking process in the above-described manner, it is possible to use some of the heat of combustion in the cracking operation by heat-exchange with the fresh incoming shale to reduce the oxygen requirements in the retort.

Another advantage of using the oxidative cracking process is that it appears to be a convenient method to effect desulfurization. Since removal of sulfur is one of the many problems met in the rening of crude shale oil, the application of the oxidative cracking process to the crude shale oil is, therefore, particularly advantaeous.

g Still another feature of the above-described process is that in order to eliminate the presence of aldehydes. ketones, alcohols, and other oxygenated organic compounds which would occur product as a result of the oxidative cracking, since for certain purposes their presence therein would be undeby conducting the gaseous product coming from the cracking reactor over or through that the oxygenated organic compounds may be converted to the corresponding olefins. This feature of the invention is illustrated in Figure .la which represents, schematically, a converter which can be used in conjunction with the system shown in Figure I. Referring to Figures I and Ia spent shale from retort 16 is conducted, e. g., by a suitable conveyor, through line 210 to converter 211. The gaseous product from oxidative cracking reactor 25 is passed through line 212 to converter 211 wherein it is contacted with incoming spent shale. The gaseous product from the converter is discharged through line 214 into line 37 through which they are' led to the upper portion of the elevatorex changer where they are cooled and condensed by the fresh incoming shale. This heat exchange serves to preheat the fresh shale. Spent shale is discharged from the converter by suitable means 215, e. g., shaking grates. Obviously, since the spent shale is to be discarded anyway, it is possible to carry out this treating step without a regeneration cycle, simply discarding shale at in the liquid hydrocarbon" the used spent j whatever rate 1s necessary to maintama reason able activity. .It is contemplatedV that thel activity"`of the spent 4shale used to convert these oxygenated organic compounds may be greatly increased by applying thereto vmineral acids,` such as Oxy-mineral acids, such as sulfuric or phosphoric acids or mixtures of the same onto the incoming spent shale to the converter. Another feature of the above-described process employing oxidative cracking is that the oxygen consumption in the retort can be reduced by burning some of the carbon still present on the spent shale with air in a separate zone below the zone of combustion but above the point of introduction of water. This can be done since not all the available carbon present in theoil shale is burned with oxygen.` Steam can be generated by introducing water directly on the spent shale in a second separate section, and can be superheated by passage through an external heat-exchanger in indirect heatexchange relationship with the hot combustion gases issuing from the rst separate zone. This feature of the invention is illustrated in Figure Ib which represents, schematically, by apparatus for carrying out this particular feature of the process shown in Figure I. Referring to Figures I and Ib, hot spent shale, still containing appreciable amounts of carbon and other combustible materials, is dropped from retort 16 by shaking grates and is delivered by suitable means 220 to a burning or combustion zone 221, for example, a furnace, which is equipped with a suitable device 222, such as an endless chan grate, for the combustion therein of residual combustibles on the shale. 'I'he furnace is supplied with air by line 224 to maintain a zone of combustion therein. The hot gaseous products of combustion issuing from the furnace pass upwardly through heat-exchange zone into the atmosphere by stack the heat exchange zone. The hot solid products of combustion (shale ash) are discharged by the endless chain grate and conveyed by means 229 to the quenching zone 230. The hot shale ash is contacted directly with water, which is delivered to the quenching zone by means of pump 46 and line 219, whereby the hot shale ash is cooled and steam is gen- The resulting steam is then conducted 'by' line 232 through heat-exchange zone 225, wherein it is superheated by indirect contact with the hot combustion gases from furnace 221, and is then delivered to distributing means 22 in the retort. The superheated steam together w1th the hot combustion gases from the zone of combustlon in the lower section of the retort supply the hlalt necessary for driving olf the shale oil from the oil s a e.

Another feature of the invention is that the preheating and retorting steps may be carried out in combination with a contact coking step wherein hot spent `shale from the retorting zone provides the contact surface as of the heat necessary to accomplish the coking reaction. This feature of the in vention is of particular interest since experience has shown that coking, particularly of the heavier fractions of crude shale oil, is especially effective as an initial step,

Ain the rening of shale oil into products meeting present commercial specifications. This above-described feature of the invention is illustrated by Figure Il which sche matcally shows an apparatus adapted to carry out this particular process.

Referring now to Figure II, fresh crushed oil'shale such as is found in vast quantities in the United States, particularly in Colorado, containing, for example, about 30 gallons of shale oil per ton by Fischer assay test, after being crushed to an averageV size of about one inch is fed from fresh oil shale hopper 81 by means 83 into an elevator-exchanger S2. As in Figure I, the elevatorexchanger is shown as a long, upright or inclined structure. Although it may have many forms it is preferably a bucket-type elevator with perforated bottoms in the buckets. An valternative would be to use a reciprocating feeder device as shown in the drawing at 84. The fresh crushed oil shale is moved upward within the elevatorexchanger and transferred by suitable means 85, such as a screw conveyor, to retort 86. The retort may be a large upright vessel lined with rebrick and containing distributing means 87 in the upper section near the top so as to evenly distribute the fresh incoming oil shale within the retort. In the lower section of the retort is located a zone of combustion maintained by a supply of oxygen from line 88 and introduced into the combussaam-,p87

'tion'fzone byilinen89. 'eSteann from rlinef 90Jisxalso inn-o- ,.duced. intozthe combustiom-zone rbyjline f89:inrrorderi flo tcontrol 4the volumerpercentage off?oxygemftherebysregu- .latingzthe extent of thev combustion zone andtthetemperfuture-.tof` the retortingl sectionvv above :.'the 'combustion zone. At the bottom: of Athev retort isf-locatednsuitable .means-93, such as shakinggrates whichpermitfhotrspent -shaletto drop from the combustion zone.

' fllhus, :the hot combustion 'gases and 'uthe' superheated steam, from'. the combustionf zone of. .the'etort ymove up- Lwardly through and countercurrentlyccontact'thefdownward lmoving mass kof? freshoil shalewithin Athefretort :and` supply the heat necessary' to drive off the Ashale :oil from the oil shale.

.The vaporized fshale. oil, swept 'along withffthe 4steam and combustiongases, leaves thefretort-vbyline 91" and -moves along :line -92 lwhich rleads tozthe ftopffsection! of .the elevator-'exchanger -Wherein .the vaporized;shale voil .and combustion gases contact theincoming fresh oil'shale indirect countercurrent'heat exchange, thereby preheat- .ingt-the vfresh oil shale while at the same;tme.the Vapor- .ized 'shale oilisk condensed upon.the 'oilshale VThe liquefied -shale oil thereupon flows downwardr to the bottom section of the elevatorrexchanger where it is .drawn oi by means of line 94 and'passed through Vheat- -exchanger 95. The shale oil leaves heatexchanger'g byline-96 and then passes throughheater 97 which is `supplied-With suitable heating meansf98 and'thenalong 'line' 99 into fractionator 100. Therein the shalefo'il may the fractionated into three fractions, a liquid fraction with anl end boiling point up to about 400 F. which isdrawn :otfas a product by linet101, a medium' fraction with an end boiling point of up to about 600 F., whichis .drawnoiffas a product by line 102.and a high-boiling oil (tarry) bottoms fraction which is drawn oivby line 104, .and which'thenpasses through heat exchanger 95 so ask to .preheat the shale `oil feed for the fractionator.

It is, of .course-realized thatv it may not be desirable to take off'two product streams from the fractionator asdescribed above. Thus, it is possible, and4 attimes preferable, to take oit all theshale oil product overhead by line 101, eliminating a sideacut medium boilingfrac- ..tion, and to draw off a bottoms fraction in sufficient .quantity via line 104 for-injection intok thecontactcok- -ing reactor.

rFromheatexchanger 95 the bottoms shale oil fraction is conducted by line 105 into contactcokingreactor -106 .at a point or points determined by the` contact time desired and/or the operating conditions.

Reactor 106 is an upright reaction chamber wherein contact cokingofthe high-boiling, heavybottomsfraction from fractionator 100 is accomplished. The reactor contains a mass of hot 'spent-shale, supplied by `means '.107 1 as the. shaking grate93 permits the hotspent shale 4to drop from retort 86.

cently high temperature, inthe neighborhood of 1200 AF., to cokethe highmolecular weight components of the heavy bottoms fraction from the ractionator. Reactor :106 operates. in the' following manner. A mass of hot `spent shale, almost completelylling the reactor, is maintained therein at a high temperature (about 1000 to 1200 F.) by the combustionof the carbon on theA spentjshale ,with oxygen, air or-an oxygen enriched gas introduced into the coking reactor by line 112. In generalk the 4heat required tomaintain the spent shale at coking temperature may be supplied by any suitableand convenient 'method The massof hot spent shale Within the reactor is `contacted therein with the heavy bottoms fraction "from the fractionator and introduced into the reactor via line 105. The temperature of this heavy shale oil fraction is rapidly increased as it contacts the hot spent shale and percolates down through the hot spent shale and as a result the shale oil is thermally decomposed with the resultant formation of some coke and lower molecular .-weight hydrocarbons.

tact coking carried out Within reactor 100 is not equivalent to or similar to catalytic cracking. In catalytic ,cracking the cracking temperature is kept W in order 5tornaintain a high catalytic activity of the catalyst employed. Furthermore, the oill fraction to becracked is selected so that very little or no coke is formed upon cracking since coke formation is 'undesirable because it *.considerably' reduces catalyst activity and life.

Inraccordancewith the invention, however, thecontact .coking iscarried-.out at a relativelyihigh -temperature,

The hot spent shale 4has a'suf-V It should be noted that the con;

.fresh oilr shale,

treating a heavy shale oil fraction (suchasfthe bottoms .fraction of fractionator 100) to.. convert theasamefinto a usable and less troublesome product. It -is realized fthat in case the quantity of heavy bottoms product: from:.the fractionator -is-insuiiicient to maketup'the required amount of recycle-oil to the;reactor -which is'necessary-,so-as to provide the heat required to preheat the incoming may bedesirableto addto-:the heavy bottoms feed-*for thecokingreactor a gas `oil fraction 'from the' fractionator, lthisy mayl be 'achieved -by taking o ff from the fractionator a product containing proportionally less highiboiling components.

The hot spentshale, after .being strippedI of possible shale oil Values by steam 'introduced into? the: bottom vsection of the. reactor' by line'113,-is continuouslyf-clis charged at atemperaturefof about 500 fromwthe reactor by suitable;'means108,r.such=asrshaking grates. The discharged spent shale still containing,-=residnal carbonas Well as some coke 'deposited thereon as af-result of contact coking' theheavy-'shaleoil fraction, maybe used Vas fuel to supply powerfsteam` anda-heatrequirementsof the plant carrying .fout -the above-described process.

The heavy shale oil fraction decomposedand-vaporized by contact with the'hot spent-shale leaves :the upperfsection of the reactorby :line 109 which istconnecteddo line 92 wherein it is commingled-.With vthe'vaporized shale oil from retort 86. This mixture-of: shale-toil vapors is then treated according'to theabovefdescribed method, maintaining a continuousprocessi-by-ftheucon- -stant supply of fresh crushed 4-shale -and :the constant removal of spent shale, fractionatedfishale oil and'f'noncondensed vapors which arefwithdrawn fromnthe lower section of the elevator-exchanger by line fto :blowereductor 111 which passeswthem to-suitable absorbing and collectingmeans for the recovery, separation and purification of the valuable componentslfthereofyegg., ammonia, light hydrocarbon gases,v etc.

Illustrative of the operating conditions and the .1 material and heat requirementsrper tonwoffoilwshale of a method of retorting Aoil shale` according-to a processeur' the invention, suchfas is-` represented byfFigure.-ll,=,:the following data are presented ibelow. Itshould' be-.Inoted that heat and material requirements willfvary over rather wide limits depending upon'operating; conditions such as,'time and temperature of retorting,aandwcontact'1coking, shale oil contentof-the oilfshale-retorted'.Whether oxygen or an oxygen enriched gas'isffemployedvtowustain combustion, etc.

Shale oil content per ton of oily shale30jg`als.

(Fischer assay test).

Retorting temperature .5900- F. Combustion zone temperature'of'retortf1200"F. Contact coking temperature 1000 F. Oxygenrequired in retorting 300 s.' c. f. Temperature of gases fromretort 900'F.

gases from Vcoking re-` 1000 F.

Stripping steam required for cokingre- Approximateactor. ly` 15 lbs. Oxygen required in coking 400 s. Cif.

As is seen from the foregoing 'description the', process is similar to the shale -oil recovery .process:described with reference to YFigure lg'wherein shale oilafter-,recovery'from oil shale'v is vsubjected to oxdativeit-crackng. The points of similarity between-.the shale'oilcfrecovery processes as exemplified by Figures l. and Vll are-.asfollows: Both Vprocesses 1 employ i .direct countercurrent; heat exchange ,inA the .elevatonexchanger.` andii'etorting: sections of the processes and'in both processes the fresh oil shale flows evenly downwardv under the influence of gravity countercurrently to :the het combustion gases. Both processes preferably employ purity to maintain the zone '.of combustionin the lower section of the retort.' Itis also possible to substitute air or an .oxygen-enriched gas for the 95% oxygen and/or steam inboth processes but'with the resultant disadvantage of thereby'causing the recovered `light hydrocarbon product gases to have a lower B. t. u. coritent and to be separated with diiculty Both processes employ a cracking process to convert the high molecular weight shale oil components into lower molecular weight components. Both processes achieveheat economy and eiiciency by utilizing the heat produced within the process as the source of heat for the recovery and cracking operations and both processes employ a heat exchange medium which carries a considerable amount of the heat required to maintain the process. Thus, in the process according to Figure I this heat exchange medium is water which is recycled in the process, absorbing heat from the retorting and oxidative cracking step and re-v leasing heat to the incoming fresh oil shale within the elevator exchanger, whereas, in the above-described process according to Figure II, the heat exchange medium is a heavyshale oil fraction which is recovered bythe fractionation of the shale oil from the elevator-exchanger, passed to the coking reactor, and which, after admixture with the vaporized shale oil from the retort, is passed tothe elevator-exchanger where it releases its heat to the incoming fresh oil vshale and is liqueed. The liqueed shale oil from the elevator-exchanger is then fractionated and the heavy bottoms fraction returned in the above-described manner to the contact coking reactor, etc.

In view of the above-indicated similarities of these two processes of the invention, it is obvious that there are possible many modifications, substitutions, combinations and variations embodying various features of these two processes. Thus it is possible, referring now to Figure II, to subject the gaseous mixture in line 92 coming from retort 86 and contact coking reactor 106 to oxidative cracking such as is carried out in the process embodied byFigure I, before passing the gaseous mixture to the elevator-exchanger since, as pointed out with refs verence to Figure I, oxidative cracking appears to be an excellent desulfurization process. This modification is shown in Figure IIa which represents, schematically an oxidative cracking reactor whichcan be used in conjunction with the system shown in Figure II. Referring now to Figures II and IIa the gaseous mixture in line 92 -is passed through line 103 to blower-mixer 119, where it is mixed with a minor amount (from l to 20% by volume) of oxygen, the resulting mixture is then blown through line 115 into the refractory-lined cracking reactorf116, wherein oxidative cracking occurs. Dry granulated coke which is produced and accumulates therein may be taken from the reactor by means of line 117. The gaseous products from the cracking reactor are then led by line 118 to the upper portion of the elevator-exchanger. Furthermore, elevator-exchanger 82 may be equipped with strippers in a similar manner and for the same purpose described with reference to Figure I, thereby eliminating the need for fractionator 100 while at the same time supplying a heavy oil fraction for the coking reactor. Also in this modication it may be advantageous. to subject the gases after oxidative cracking to the action of hot spent shale (obtained by the burning of the coke and residual carbon of the spent shale from .reactor 106) in order to convert any oxygenated organic compounds therein to their corresponding olens in the manner set forth and described with reference to the process of Figure I.

' Furthermore, referring now'to Figure I" it ispossible to inject the quenching oil from line 29 vinto the hot shale of retort 16 above the combustion zone so as to subject the oil time thereby eliminating the quenching andoxidative cracking steps of the process of Figure I and to a cer- .tain extent changing the I to a process similar to except that contact coking reactor 106 is eliminated and thermal cracking instead of contact coking ige-employed. Other'possible variations and combinations of the-proef oxygen.. of approximately.

supplied by means of line 114, and

to thermal cracking and at thefsarner process represented by `Figure that represented by` Figure IIl e'sses set forth by Figures vI and:II areV as follows: the process represented by Figure lII may. be modied by the `elimination of contact coking reactor 106 and thermal cracking of the heavy -shale oil fraction from line maybe carried out in that section of the retort above the combustion zone. The heavy shale oilfraction may be preheated by indirect heat exchange with .the hot spent shale from the retort. This featureV of the invention is illustrated in Figure IIb which represents, schematically an apparatus which can be substituted for the contact coking reactor shown in Figure II. Referring to Figures II and IIb, hot spent shale from retort 86 is delivered by means l244 to a heat-exchanger 240. The heavy shale oil fraction -from line 242 is conducted through the heat-exchanger in indirect heat exchange relationship with the hot spent shale therein, and is then delivered by means of line 241 into the retort at a point above the zone of combustion therein.

Also, still with reference to the process of Figure II it is possible to eliminate fractionator 100 and substitute in place thereof separation devices such as separator 41 and separating means 27 employed in the process of Figure I to affect fractionation of the shale oil. Similarly, with reference now to Figure I, it is possible to eliminateV separator 41 and separating device (stripper) 27 and to substitute in place thereof fractionator 100 such as is shown in Figure II to accomplish the same purpose. Wherever in the above processes an elevatorexchanger and a retort are used in combination, as in Figures I and II, it is also possible and oftentimes advantageous to employ the elevator-exchanger and retort combinations shown iny Figures IV and V Many other modications and vcombinations of the above processes are possible as will be evident to one skilled in the art.

Still another feature of the invention, which feature is employed by applicants preferred embodiment of the invention as illustrated by Figure III, is that the preheating, retorting and fractionation of oil shale and shale oil are carried out in a manner similar to the method described with reference to Figure II except, however, the oxygen requirements of the process are greatly reduced and more ecient utilization of the available heat is achieved.

Referring now to Figure III, fresh crushed oil shale such as is found in vast quantities in the United States, particularly in Colorado, containing, for example, about 30 gallons of shale oil per ton by Fischer assay test, after being crushed to an average size of about one inch is fed from fresh oil shale hopper by transfer means 121 into elevator-exchanger 124. The elevator-exchanger is shown as a long, upright or inclined structure. Although it may have many forms it is preferably a bucketupward within the elevator-exchanger and transferred `by suitable means 126, such as a screw within the retort. At the bottom of the retort is located suitable means 129, such as shaking grates, which permit the hot spent shale which still contains an appreciable amount of carbon and other combustible material to drop therefrom. Also in the lower section of the preferably above the shaking grates is located distributing means which is supplied by line 131 with the hot gases and vaporized shale oil from contact coking reactor 133.

Thus, the hot gases. and vaporized shale oil conducted to the retort via line 131 move upwardly through and countercurrently contact the downward moving mass of fresh oil. shale within maintain the temperature within the retort in the neighborhood of from about 900 to about 1000 F., preferably at about 900 F., so as to drive off the shale oil from the oil shale therein.

The vaporized shale oil, swept along by the hot gases from the contact-Coker, leaves the retort by line 132 which leads to the top section of the elevator-exchanger wherein the vaporized shale oil and hot gases contact the incoming fresh oil shale in directcountercurrent heat exchange, thereby preheating the fresh oil shale to retorting temperature while at theA same The fresh crushed shale oil is condensed uponfthe oil fshale.. Thercondensed' and liqueed shale oil ows :downward :through the Loil shale to the bottom section ofthe elevatorexchanger..y where it 1s drawn off by line 134. The non-condensedi gases and vapors are drawn olf .from the elevator.-

exchanger at the same time .via linef135 .which is conf.

nected to the suction sideof` blower-eductor 136 from which they pass via line 138 to 'suitable cleaning, recovery and storage means of the valuable and the light hy in order to provide for fa for the recovery and/or separation components thereof, such. as ammonia. drocarbon gases... It Vis pointed out that morefcomplete recovery of the light, more volatile hydrocarbon fractions it may .be desirable to interp ose a condenser (not shown in Figure Hl) with a suitable coolant, such as water, shale oilproduct, air, etc., between:

line 135:l and Iblower-eductor 136 in order to condenseand remove the more volatile hydrocarbons from the ordinarily non-'condensable gases.

In the operation `of the process, hot spent Vshale from which .shale oil has retort byvshakin able means 139' for example, l able device 141,`

been driven olf :is Idropped from the g gratesand .thenis rdelivered by suit- 'to a burninghor combustion zone 140,

a furnace, which is equipped .with a suitsuch as anaendless chain r grate; orthe combustion .therein of the residual` combustible'fmatter.

on the hot spent shale hereinbefore the Vfrom the retort..- As pointed outv `spent shale fromthe retorting zone con-..

tains a considerable amount of. combustible. matter, such as carbon. The 1s burned Within or an oxygen-co zone of combustionl combustible :.matteron. the spent' ishale the furnacefwhich '-is supplied with air ntaining gas -byflinef1142lto maintain a therein. This airror oxygen-containexchange zone. (shale ash) are less chain grate a The hot-solid products of combustion discharged from theffurnace .by the Iendnd conveyed by means145'to the :contact` coking reactor 133.

The liquefied shale oil from the elevator-exchangerlis conducted by line 134 throught heat exchange `zone- 144,

wherein the temperatureofsaid'shale oil is raisedfto from: about 600 to about:800":'F., preferably in thene1ghintd-fracti'onator 1483i Therein theA shale oil may befractionatediintothree fractions, a toplight fraction with -an Vend boilingpoint up .toabout 4005 F., which is drawnioas a product by Ilinel49ga middle,

medium fraction F., which is drawn .offas bottom, heavy high boiling off .by linel151.-V connected with' 1 ywith an endlboiling point of 'about 600 fraproducty by line 150 and al (tarry) fraction'which'is drawn Pump 152,# thesuction side of which` is ine 151 andi i hel discharge' side of lwhich is connected toI line 154 acts in combinationfas a reboiler, the -liquid `bottoms fractiony being-fpassedvthrough andl heated via line 154 withinlthe heat Vexchange Zoneand then returned to the lrat-ztionator.

It is, ofv course, realized-that-:it may fnotf-befdesirable to take off.A two as described above;

to take `off all.. the :liquidVshale oil product preferable,

overhead by line y149;'elirninating the:

boiling fractionl means. of .valved in sulicient quan productl streams fromf thefractionatorl Thus, it` is possible', Vand-at times side-cut mediurrr and -to drawoft a bottoms fraction -by '.line.155,L which connects'v with line-154,1

tity to maintainthe-'desired heat-exchange relationships l.throughout :the.process. lafter injection. 'intof the .contact coker Valved line 15S withdraws ractionator vbottoms vpasses said-bottoms 4exchange zone fora ture up to from .ably.900.

reactor. via lines determined ,by the contactL :time Verating condition reactors.

at least aportioni offtheiraction'frorn -reboiler '.line; 154,` land '-:fraction'i throughrtheffurnace ;heat. timecsutlicientto *bring itsftempera-t `about .800 toLabout 1000. 'F.,' prefer-5 F., and then iniect'fitxinto,thexcontact coltingr 156;'.158 andfl59f at a .pointfor points.v desired anddor tthe. :op-.-

Contact coking reactor 133.'is an upright reaction chamber wherein-contact Vcoking-of ,the-"high, boiling,yl.ieavy bottoms fractionrom fractionator y148 isl accomplished.

The reactor contains a thereto bymeans 145 permits the; ash

- ash `^is maintaine mass; of .hot f shale, ash supplied as -the :endless chainfgrateflftl; to drop, fromzrfurnace-'MEL Theishaled therein` atga sucientlyv high .temperazf,

fromthe fractionator.-`

ture,:.fromf: aboutnSSO fztotabout d 2005i.; preferably vdni the neighborhoodfoffabout'SOOTE; to. cokeitherhigh :nosl lecular weight components. of the heavy bottomsfractionf Reactor y13:3 operates in `thezfollowing manner;` Amaszs of hot burned spent shale. (shale: ash) ,almost 'completely t filling .the reactor and..which'may containggsome .residuale unburned carbom. is. :maintained :therein rat ga higlrzfterne perature (in thefirangefzof 850. 'toflZOQi F1),v Although: the shale.;ash is .at :least withinrthisv temperature-'rangen immediatelyattent-discharge: ;frorrrutherzfurnace, due ito'; radiation andother heatlossesein:additionftotherheati; required. to .Coker thefheavy bottomsrgshale; oilwfractionv injected therein', itA ist necessary :itocsupply .heatttof the .re-.z-

actor inorderto ma1nta1npthecdesiredfoperatingctemfzperature.` This-heat mayibe ,suppliedchy-combustion of. any residual .carbon` asathesshale; ashz'orfthe combustion of the coke deposited:thereon: as :.a: resultzrof contact; colting .the heavy bottoms-..fraction:z. Furthermore; this-1 heat may also .be obtained-:by the.:combustion-,0f.a por-x` tion of the .injected:shale-.bili.v Theiaforesaid.1combusf z tion may be maintariedjay a supplyfofcxygen orair1or; an oxygenV enriched .gasfntroducedfzinto .zreactor,:` for` rex. r ample, at the lower sectionfthereofnviasline 160; Inffgen'r;

i eral the heat required to maintaingthe shale ashiat colting',

temperature mayf be supplied. `by-anysuitable :and cou., venient method,v for; example; ,thezhotfiue :gases ffrom; stack 145,-orsuperheated steam:

The mass of;hot shale :asin.withinrthefreactor;.is'.conV tacted thereinxwith Ithe heavy-bottomsrfraction from-the: fractionator and ,introduced into .thecreactor'Y viaa lline or. lines 156,- 158 'and `159:- Theftemperature of ithis'heavy' shale oil fractionjis' increased-asritcontacts. the hotshale'.` ash'. and percolates'V down."l therethrough-g; and* as a result: the high molecular Weight components thereof are ther. mally decomposed with the resultantformationof some cokeand lower molecularnweight hydrocarbons.'`

As pointed outwhereinbefore-rWithf referenceuto Figure: H,- the Contact cokng :whichz is carried out Within the; reactor 133 isnot I-equivaleut-to for; similar `.to catalytic. cracking. lnfcatalyticx crackingihe .cracking temperature is kept .low inorderitotzmaintain'ahigher,catalytic'ac. tivity ofthe .catalyst.;employed.. Furthermore, .the oilfraction: to be f cracked `isselected:4 sothat veryY littlezor r no vcolte is formed-upon crackingrsince cokevformationa is 'undesirable because itV considerably reduces fcatalyst` activity and life. Furthermoreffor-this particular applica-1v tion'contact-cokingg-has'been found to befa satisfactory? method4 of treating a heavyshaleoil't fractionV to convert-` 2 the-same into a usablefandfless. troublesomefproducb.

As pointed1out-rhereinbeforeyit is realized that itzmay; be desirable to eliminate .thearniddletsidecut:fraction.takenn off as product via -line 150.rfrom fthefractionator-fandfto; increase the-.amountfof the heavy,'bottomsfraction inf.Y

jected intow-reactor in-order1to supplythe requisitefhot@ vapors from the reactorto `the. retort,. which vapors aref. necessary to heat theYoilwshaleatherein-v and to stripafthe, shale oiltherefrorn.Y it is Valsopossible-by:meansfofa val-ved line. lkwhich connects. lines 13E: and 132,the1 inlet and..;outle t .vaporey Alines of. the -.-retort,-. respectively,-v` to bypass they retort-:with at :leastz'avportioncr all of, the: hot shale,- oil` vapors,fromtheqreactor;- Thismay be advan-. tageous inf order` to avoidz'excessiyefzpressurerdropthrough-f the .retort fwhen a' largeqvolume; ofvgasvgandor vapors:

Y are .passed-therethrough.: No lossrofrheat occursssince' the ;hot\;vapors from line 161'1are carriedvia linerllrto` contact andtzpreheat the. freshwincomingfoil'shale inthe elevamr-exchanger. lt is also;desirable to supplyfoxygenf, via :line:v 123 toxdistributingameans 130 dnsthe lowernsec-.iK tion .ofA the :retort :so :asto supply at vleast a portion'of. the i heat `required to retort oil; :shale-by ,the combustiongo' the residual:` carboutonrftheffoil shale. .f The-,combustion-- gases.y alsofserveto zsweepgoutsshale.. oil .vapors from. .the retort via line 132.

, 'l'hehotjsh'ale aSh;;.'after. being st-ripped-.of.possible*shale oillvaluesgby flow pressure steam-introduced into-fthe' lower section of thetreactor vi-a lin'etltbeneathline 160',-` is continuouslygdischarged frornfthefreactor-at a suitable temperature,.-forfexamplet inysthe. ,range-.from-- aboutl SOO-V F. to about 9005' byj-zstablewmeansill, ,such as shale, ingfgrates; Thezhot disehargei shalepashiiwhich';contains cokedeposited@thereon-as a-result of i contact-colting the. heavyyshaleeoil f1-actions@ lb-.assperhapsfsome resida ualwcarbomnmay;bequse :a tuelrfto supply-f atr-leasti a .-.pe1;ric r1.arfni@verneemtendureae.tenurernentstfv a plant carrying out th'e above-'described process or`the.`

heat may be recovered therefrom by heat-exchange, such as with air to preheat the same beforev entering the,

the invention, such as is represented by Figure III, thev following data are presented below. It should be noted that the heat and material requirements will vary over rather wide limits depending upon operating conditions such as time and temperature of retorting and contact coking, shale oil content of the oil shale retorted, etc.

Shale oil content per ton of oil shale 30 gals. (Fischer assay test).

Retorting temperature 900 F. Contact coking temperature 900 F. Oxygen requirement in retorting About 150 s. c. f. Temperature of gases leaving retort 900 F.

550,000 Bft. u.

80 gals.

430,000 B. i. u. y

Heat required to raise oil shale temperature from 60 F. to 900 F.

Heat delivered to oil shale by retort products.

Temperature of gases leaving contact- Coker.'

Quantity of heavy oil recycle to contact-Coker.

Heat delivered to oil shale by coked recycle oil.

Oxygen required in coking About 150 s. c. f. Temperature of shale ash from lcontact- 850 F.

coker. Stripping steam for contact-coker About lbs.

The above-described process, as illustrated by Figure III, despite its many advantages over the process vas illustrated by Figure Il is still very similar thereto, the main difference being the use of a separate combustion zone in the process of Figure III rather than maintaining a combustion zone with the retort as in the process and retorting operations may be carried outwithout employing the oxidative cracking step or the contact-coking step in combination with the oil shale retorting step. This embodiment is illustrated in Figure IV which 'schematically shows an apparatus adapted for carrying out this particular method.

Referring now to Figure IV, fresh crushed oil-shale is fed from fresh oil shale hopper 50 into preheater 51. The fresh oil shale is moved upwardly within the preheater by any suitable means, such as a reciprocating feeder device 52. When the oil-shale reaches thel top section of the preheater it is transferred by suitable means, such as a screw conveyor or rotating ploughs 53, driven by means 54 along conduit connecting means 55 into the top section of retort 56. Air or oxygen is introduced into the lower section of the retort through line 57 to maintain a zone of combustion therein. Water may be `introduced via line 58, for the purpose as described with reference -to the process illustrated by Figure I, that is, to cool and quench the hot spent shale and to thereby supply steam to the combustion zone. The lower section of the retort, below the zone of combustion, is equipped with a spent shale discharging means such as illustrated by means 59. Thus, it is seen that the hot combustion 'gases and steam which is superheated as it passes through the combustion zone, arising from the zone of combustion travel upwardly, countercurrently to the downwardly moving body ofoil-shale within the retort and drive olf and strip the shale oil from the oil shale. The hot gases now commingled with vaporized shale oil then move through said conduit connecting means or vapor line (not shown in the drawing) in case a screw conveyor instead of a rotary plough wasused, into the top section of the preheater and pass downward, countercurrently `to the lupwardly, movingl the `operating conditions and .the Imate-H through line .62.l Afmoditication of an embodimentof the invention de`-.A scribed with reference lto vFigureiIV is illustrated in- The condensed shale oil. means of lines 60 and 61 Figure .V.

In accordance with and the preheating zone of the apparatus represented in Figure IV are combined in a unified structure wherein the'retorting zone is an upright annular zone surrounding r the preheating zone, from which it 1s separated only by an upright dividing wall extending not all of the way to the top of the combination vessel and leaving 'at the inside top thereof a suitable inter-connecting space or opening for the from one zone to the other. More efficient heat transfer of heat from the retorting zone to the preheating zone 1s eff/ected by use of the apparatus illustrated by Figure Referring now to Figure V fresh, crushed oil shale is fed from oil shale hopper 70 into preheater (preheating zone) 71. The fresh oil'shale is caused to move upwardly within the preheater by any suitable means, such as reciprocating feeder 72. When the oil shale reaches the top of the preheater it passes over to the retort (re.- torting zone) 74. It should be noted that the preheater is mounted concentrically within the retort and that the annular space between the preheater and the retort serves as the retorting zone. Air or oxygeny is admitted into the lower` section of the retort by means 75 so as to maintain arzone of combustion therein. Water may be introduced via iine 78, if desired, for the same and similar purposes as described in connection with the processes as illustrated by Figures l and IV. The lower section of the retort, below the zone of combustion, is equipped with a spent shale discharging means such as illustrated by means 76. Thus, the hot combustion gases (and superheated steam) arising from the zone of combustion travel upwardly countercurrently to the downwardly moving body of oil shale within the retort and drive oi and strip the shale oil from the oil shale within the retort.Y The hot gases nowcommingled with vaporized shale oil after passing through the retort, then pass downwardly through the preheating zone countercurrently to the upwardly moving fresh oil shale, which is heated by said hot vgases and which at the same time condenses the vaporized shale oil. The condensed liquefied shale oil product is collected by means 77 and/or. 79 and drawn off as a product through line 80.

Still with reference to Figure V it is pointed out that it is possible to carry out the process as illustrated by Figure V by modification of the apparatus thereof so that therelative location the retort (retorting zone) with respect to eachother heating zone of Figure V as the retorting zone (and the retorting zone) and the retorting zone of Figure V as the preheating zone. It is understood, of course, that the other necessary changes in the location and arrangement of the oil shale feeder and air, oxygen and/or steam supply lines must also correspondingly be made.

Another feature of the invention, which feature is Vemployed by applicants embodiment of the invention as illustrated by Figure VI, is that the preheating and retortingfof oil shale are carried out in a manner somewhat similar to the method described with reference to Figure IV except that the heat required to bring thev ture is furnished by hot shale oil vapors which shale oilv has previously been subjectedto the temperature and pressures of the well own viscosity-breaking conditions. Furthermore, the combustion of the oil shale to supply the necessary heat for the process does not take place within the retort but rather in a zone separate therefrom, such as a furnace.

Referring now to Figure VL'fresh crushed oil shale such as is found in vast quantities in the United States, particularly in Colorado, containing, for example, about 30 gallons of shale oil per ton by Fischer assay test, after being crushed to an average sizeof about one inch, ls fed from fresh oil shale hopper ,170 by transfer means 171 into elevator-exchanger 172. The elevator this embodiment, the retortingzone free movement of particulate material of preheater (preheating zone) and meedoen material itovdroplutherefrom.. Alsouinllthellower see-tiem 15 ofstheretorttandrpreferablywabove@ the .shaking A g1=ates-1fis.x locatedfdistaibuting means `lsiwhic'h is suppIiedbyvvalved-t linestll and 1182Lcarrying. hotJvapori-zed Lshaleoil land oxygeniorfargf respectivelyir ranger of mboutzSOOti 2toabctut` :9005 F.; preferably; about. 8503:; F;,f.,.etc.;.'shalezoil having ibeen'ssubjected. .thereinuto: viscosity-brcakingnconditions `of .temperaturesl andspres-l sure, for example, a temperature from about 80031011 5 ahoutSSO? Ftunderialpressure offromabout 2001tofab'out tosheauand driver-off: shale :oil

SBOIbsepee squarerinch'.

Fromfh'eatfexchangerl the rhot shaleroil movesfalongi line' 184 fromewhichta#portion :or all-0f the: shalel oil: maybe: admitted wia. line-.1812 into vthe.l `retort in :orderi .from the loil: shale therein Thegaseousprodncts from'theV upper section fof ythe retort 1 leaveivia line 183'Swhichris:connected'with line-184 and: along:whiolrftl'leyfA are .thenvA conducted to Jthefelevatore exchanger.

It may beJ'desirablein orderto maintain a retorting temperaturewithin the retort to admita supply of oxygen or air thereto via line'182.- The 'oxygen'unites with the combustible matter 'on' the oil shale 'and'thereby supplies the'small amount ofrheat necessary to maintainV the de-Y Thus;f thee-honi gasesr` movesupwardI-y' throughfandf-Zfsired retortingrtemrnerature.` It is possible and some-y countercurrently contact the downward moving v,mass of3 freshri oil shalewithinthe retortandi supplz'thbheat necessary ito maintain i a' 4vretortirig"t:finger-atine-lwithij th retort;` for'` example; in-rtheneighborhood 'oflfrom abioutA 700lf'tot-about 1 1005' F.'g preferably#witliiri'thirange 10003113.; ab iaboutl-'QOOPf'Frg' so was to'driv'elofftiiti"shaleS oilfromfthefoil shale thereiria` T he' `gasesland Evaporized 'rshalefoil leave thefretortf-via; line y 183,fr enter line 184 which leadsitothetophseetionfA ofi'fthe'elevatonexchangenwhereiriJ-thesvaporizedshaicile; and-@hotA gasesl contact' thedncomingf fr'eshhoil"'shaleJ i113 directy countercurrent heatexchange;therebyipreheatirigJ the? fresh oil shalegupto. retort'ingl `temperature; wliii=-atf the-same 'time '-the-vaporizedshaleoil` is` condensed` upon:

downwardA throughlthe oilfshale \to `the bbttonrsection of `'the =elevatorexchanger wheredt is drawnof by nline" 18551 The noncondensed gases and "vapors are drawnf'off fromt theelevator-exchangervia"line' '186 which is foon: neeted-"torthe -suctiorr siderof Vblo.fv'er-ednc'tor 18"frorn whiclntheyipass -via"line' 1S8to :suitablescleaningrecov=2 er'yand-v storage :means: for -the3recoveryj and/or separa.:` tionof th`e `valuable componentsthereof,lsucl'as ammonia; and th`e^light-hydrocarbon gases; Itfis lpoiiitedf-fout"that` in'order-to 'provide `for' a more complete 'recovery'of th'e` light', more* volatile" hydrocarbon fractions'it 'maybe desir# ablevtoeinterposea condensernot'shown in'Figure"VI')" with afsuitablel coolantgsuch as watergshaleoil product; ai; etc.; Abetween'liue A 186" andblower.eductor: V'187'."in ordertoondense and remove1the=morevolatile hydro? carbons from the ordinarilynon=condensabl"gases'.r:-

Infthe 'opera-tion of "the processrhotspent` shale "from. whichfsha'le `oil' l'has A`beendrivenrfoi'is TOPPCd fromfthe retort by Lthe shakingjgrates -and J'their delivered Eby suitable'- means -189lto-aaburningior combustion for"eXamp-le`, Ya furnace,; which.` isY equipped" witl 'a .suitf al l-de'vice191;` sucheasamendiesschaim grforrthe combustiontherein-'of tthe hotsperit'sliale 'from'the retort? As Apointed outa hereinbetore; -the spent' shalefrom "the" retorting zone containsa considerable amount ofcorrr# bustiblmatter sachsasecarbon: The''combtlstitildfmatter on-the^spent'shale 'is' burnedrwithifrthe furnace whiclris"V suppliedwith-f'airtor-'arroxygen containinggasivizrline 192to maintaintfazoneocombustion therein. Thehot gaseous* products'offcombustionron `leaving ahem-furnace; 653

pass V'throughfheat-exchangeizonee 19d ijand are thenrdisf siprsted intollthe .-atmosphere'lbyestack `1943whichtisf con^ nectedtowth'e heatfexchange.zone:` Tfie'h'ot, solidpro'dai ucts' offc'ombustion"(shale'ash) arcidischarged frornthez drawn via' line 2tl0lfto thesucn which `dt is forcedl along )linie '-2432 t'o heatiexshangertilocated :-withi;n` theheat-:exehanger fvzonefr Thefshale Soilrecycler' from product: irumdowrrmtanlrenters --fheatLtg exchanger 203 at.af,temperaturerof abouti/100W emergems'herefrom .viaflinefelld at ter'nperaturetainff.the@i tmesmdesirable in the voperation.of"theprocess for the" shale oil vaporto by-pass the retort completely andpass. directly to'the elevator-exchanger. This maybe advantageous if,the.p ressure drop .through the retort is too.

This ispossibleV since the'oil shale from the elevator-exchanger will thereby be brought up to retort-L ing temperature before'admission into the retortand since retortingshale oil from oil shale is primarily a soakingoperation; verylittle heat being krequired 4to actually vaporizeshale oil from 011 shale once the retorting -temp'erature has been reached.'

Illustrative ofthe loperating conditions and the material andheat requirements per tonof oil shale of a method. of retortingI oil shale according yto a process of the inven-A ,by-.Figure VI, the following datafare presented-;be10w.. It should bev notedthattthe!` heat and-` material requirements will' vary over rather Wide'limits Ydepending .upon. operating'conditions suchf as. timetandtemperatureof retortingt-and` contact coking,.V

40 shaleoil contentqotheeoilshale.retorted etc.

'30 Quantity of recycl'eto viscosity `breaker Retortingrtemperature. 900"F. Oxygen* requirements-in retorting About 150 's. c. f;` Tmperatureof'gases'leavingretort; 900 F.

Heat require'dzto raise oilrshale temperature fr'om`60' LFJ to 900.0A F'.'

Heat delivered.:v to i' oil. shale-1 by retort products 430,000 B.' t. u..

Temperature of products from viscosity breaker.VIH

Heat delitferedto 'oil ",shale lb'y ,viscosity broken'recycle.'

The processes of the present inventionrriayvbe'fvvidelyl variedrast-to conditions-:of temperature;y pressure, `ratefoi through-putlamountof reactants; qualityrof product' de-` sire'd', ctc.,L'asfbrought-'outfintthe above-descriptions: For

SOobvionsureasons, it-is-`preferredlltooperate kthe invent-ion* atsrabout z'ttrnosphericI pressure.

Theiinventiontis adaptedfor the-'recoveryof 'oils'fr'on'w any solidsubstance; but it is yparticularlyfdirected totheVL recoverywoflhaleoilfromfioil shale.

In @addition-' the foregoingf description'ofthe-'processesisflnotito beltaken'las limiting the inventionsince-'many variations lofl-ith'e processes; as pointed Vout,V may be madeA bythose/skille'dz ini the'dart lwithin theA scopeV voffthe invenl `tion.3A

l; Asystemwfor recovery'lfof-:shale-:oil frmoil"'shalei comprisingI firil combination an uprightj heat exchangen atv-upright retortirigfWesseland" aA cracking-reactor, saidZ upriglt'heat exchanger "providedtherein' with elevating'j T5? means' for elevating#,partculateisolid material;- and pro-j vided 'thereiri `)with-y 'intermediate collecting.; meansfori liquefiedproduct and?? furtherf provided *with* liquid 'and` gaseousfcollecting' meansin :the bottom thereof, conduit meansconnecting-fthe-upper ends'of said heat exchanger' S08- a-nd-fsaidtlfetortsvesselfndeadapted for stransferring,para` ticulatesolidmateriabifrom saidi'h'eat 'exchangerto Asaid1 retortflvessel; saidfretort' vesselAx provided^with -anoutlet. opening nearvth'e uplivere'nd thereofand'further-providedl witlil two' separateefeed vinletsnearrthe 'bottomL thereof' nefata higherrposition thanath'elother'and' afdischargef' outlet opening near lopening at'the bottom for removal of particulate ,solid material therefrom, a first conduit means connecting said the upper end of said retort vessel with an inlet opening at one end of said cracking reactor, a second conduit means connecting said heat exchanger with an intermediate point of said first conduit means, means for introducing oxygen into said rst conduit means between said intermediate point and said cracking reactor, said cracking reactor provided with an outlet opening at the other end thereof and conduit means connecting said outlet opening of said cracking reactor with the upper section of said heat exchanger.

2. An apparatus for the recovery of shale oil from oil shale comprising a unified upright retorting structure closed at the top and having an annular zone formed by an uprigr t vwall extending within said retorting structure not all the way to the top of said retorting structure permitting inside the top of said retorting structure free movement of particulate material across the top of said upright wall, said unified structure being provided at the outside lower section thereof with inlet openings adapted for the passage of oxygen and steam therethrough, with a lower outlet opening adapted for the passage of particulate spent oil shale from said annular zone, and with an inlet opening adapted for the passage of particulate fresh oil shale into the enclosed space formed by said upright wall, `and said unified structure being provided at the bottom thereof with an outlet opening for the withdrawal of shale oil from said enclosed space, and plunger means associated with said unified structure for forcing the oil shale in a compact column upwardly through said enclosed space.

3. A method for the recovery of shale oil from oil shale which comprises; introducing preheated oilJ shale into the upper section of a retort; causing a bed of said preheated shale to move downward, countercurrently to a stream of hot combustion gases whereby heat is supplied to said oil shale; producing said combustion gases by maintaining through the use of oxygen a zone of combustion in the lower section of said retort; ejecting hot spent shale from said combustion zone of said retort into a contact-coking reactor; injecting into said reactor a heavy shale oil fraction to contact said hot spent shale therein; conducting the efiiuent shale oil vapors from said retort and said reactor at a temperature below the threshold temperature in admixture with oxygen to an oxidative cracking reactor and effecting oxidative cracking of the admixture therein; conducting the effluent vaporous oil-containing product from said oxidative cracking reactor to contact in direct counter-current heat exchange relationship with fresh oil shale in a preheating zone to produce said preheated oil shale and to condense a portion of said vaporous products; removing liquefied shale oil from said preheating zone to a fractionating column and fractionating said liquefied shale oil to produce shale oil product and said heavy shale oil fraction.

4. A method for the recovery of shale oil from oil shale which comprises; introducing preheated oil shale into the upper section ofa retort causing a bed of said preheated shale to move downward, countercurrently to a stream of hot combustion gases whereby heat is supplied to said oil shale; producing said combustion gases by maintaining through the use of oxygen a Zone of comhustion in the lower section of said retort; ejecting hot spent shale from said combustion zone of said retort; preheating a heavy shale oil fraction by indirect heat exchange with said hot spent shale; injecting said heavy shale oil fraction into the upper section of said retort above the combustion zone and thereby subjecting said heavy oil fraction to thermal decomposition; conducting the eluent shale oil vapors from said retort to contact, in direct countercurrent heat exchange relationship, with fresh oil shale in a preheating zone to produce said preheated oil shale and to condense a portion of said shale oil vapors; removing liqueed shale oil from said preheating zone to a fractionating column and fractionating said liquefied shale oil to product shale oil product and said heavy shale oil fraction.

An apparatus for recovery of shale oil from oil shale comprising in combination an upright heat exchanger, an upright retort vessel, a contact-colring reactor and a fractionating vessel, said upright heat exchanger provided therein with elevating means for elevating particulate solid material and further provided with liquid and gaseous collecting means in the bottom therei8 of, conduit means connecting the upper ends of said heat exchanger and said retort vessel and adapted for transferring particulate solid material from said heat exchanger to said retort vessel, said retort vessel provided with an outlet opening near the upper end thereof and further provided with a feed inlet near the bottom thereof and a discharge opening at the bottom for removal of particulate solid material therefrom, conduit means connecting said discharge opening of said retort vessel with an opening on the top of said contact-coking reactor, said contact-Coking reactor provided with a bottom discharge opening for removal of particulate solid material therefrom and further provided with a feed inlet opening and a gas outlet opening, conduit means connecting said gas outlet opening of said contact-coking reactor and said outlet opening near the upper end ofsaid retort vessel with the upper section of said upright heat exchanger, said fractionating vessel provided with a bottom discharge opening, a top discharge opening and a side feed inlet opeuin'g, conduit means connecting the bottom of said heat exchanger to said side feed inlet opening of said fractionating vessel, and conduit means connecting the said bottoms discharge opening of said fractionating vessel with said feed inlet opening of said contact-Coking reactor.

6. A method for the recovery of shale oil from oil shale which comprises: introducing preheated oil shale into the upper section of a retort; causing a bed of said shale to move downward countercurrently to a stream of hot combustion gases and superheated steam whereby heat is supplied to said oil shale; producing said combustion gases by maintaining through the use of oxygen a zone of combustion in the lower section of said retort and producing said superheated steam by introducing water directly upon the hot spent shale from the zone of combustion at a point below the zone of combustion and simultaneously cooling said hot spent shale and superheating said 'steam upon upward passageof the steam to and through the combustion zone; ejecting the spent shale from the retort; cooling shale oil vapors emerging from said retort in a quenching zone with a heavy oil fraction produced in the process as hereinafter described to produce a shale oil mixture; conducting said mixture in intimate admixture with oxygen to a cracking reactor and effecting oxidative cracking of said mixture; contacting vaporous oil-containing product from said cracking reactor in direct countercurrent heat-exchange relationship with fresh oil shale in a preheating zone to produce said preheated oil shale and to condense a portion of said vaporous product; removing said heavy oil fraction as a condensate from an intermediate point of said preheating zone; removing the uncondensed gases and further liquefied product from said preheating zone and separating the water from said liquefied product.

7. A method for the recovery of shale oil from oil shale which comprises; introducing preheated oil shale into the upper section of a retort; causing a bed of said shale to move downward countercurrently to a stream of hot combustion gases and superheated steam whereby heat is supplied to said oil shale; producing said combustion gases by maintaining through the use of oxygen a zone of combustion in the lower section of said retort and producing said superheated steam by introducing water directly upon the hot spent shale from the Zone of combustion at a point belowthe zone of combustion and simultaneously cooling said hot spent shale and superheating said steam upon upward passage of the steam to and through the combustion zone; ejecting the spent shale from the retort; cooling shale oil vapors emerging from said retort in a quenching zone with a heavy oil fraction produced in the process as hereinafter described to produce a shale oil mixture; conducting said mixture in intimate admixture with oxygen to a cracking reactor and effecting oxidative cracking of said mixture; conducting the vaporous oil-containing product from said cracking reactor to a converter to contact said vaporous oilcontaining product with said spent shale so as to convert the oxygenated organic compounds resulting from the oxidative cracking step to the corresponding hydrocarbons; contacting the vaporous product from said converter in direct countercurrent heat-exchange relationship with fresh oil shale in a preheating zone to produce said preheated oil shale and to condense a portion of said vaporous product; removing said heavy oil fraction from an intermediate portion of said preheating Zone; removing the uncondensed gases and further liqueed product from said preheating zone and separating the water from said liquefied product.

8. A method of retorting oil shale which comprises; introducing preheated oil shale into the upper section of a retort, causing a bed of said oil shale to move downward through a retorting zone in said retort countercurrently to a stream of hot combustion gases and superheated steam in proportions and sensible heat content and having a temperature suflicient to retort the oil shale to shale oil and spent shale; producing said combustion gases by maintaining through the use of oxygen and the spent shale from which shale oil has been substantially vaporized a zone of combustion in the lower section of said retort; producing said superheated steam by introducing water directly upon the hot spent shale from the zone of combustion at a point below the zone of combustion and simultaneously cooling said hot spent shale and superheating said steam upon upward passage of the steam to and through said combustion zone; and removing the cooled spent shale from the retort.

9. A method of retorting oil shale which comprises countercurrently contacting oil shale in a retorting zone with a combined stream of hot combustion gases and superheated steam in proportions and sensible heat content and having a temperature suihcient to retort the oil shale to shale oil and spent shale; producing said cornbustion gases by maintaining through the use of oxygen and the spent shale from which shale oil has been substantialy vaporized a zone of combustion in one end of said retorting zone; producing said superheated steam by introducing water directly upon the hot spent shale from the zone of combustion at a point downstream from the combustion zone along the direction of movement of the shale and simultaneously cooling said hot spent shale and superheating said steam upon upward passage of the steam to and through said combustion zone; and removing the cooled spent shale from the retort.

10. A method of retorting oil shale which comprises: introducing preheated oil shale into the upper section of an enclosed vertically extending retorting zone causing a bed of said oil shale to move downward through said retorting zone countercurrently to a stream of hot combustion gases and superheated steam whereby heat is supplied to said oil shale; maintaining through the use of oxygen a rst zone of combustion in the lower section of said retorting zone to produce said hot combustion gases; burning shale from said rst zone of combustion with air in a second separate zone of combustion; passing hot spent shale from said second separate zone of combustion to a separate shale quenching zone; quenching said hot spent shale by introducing water directly thereinto; contacting the resulting steam with hot combustion gases from said second separate zone of combustion in an external heat exchanger in indirect heat exchange relationship to produce said superheated steam; introducing said superheated steam into said retort at a point below said first zone of combustion; cooling shale oil vapors emerging from said retort in an oil quenching zone with a heavy oil fraction produced in the process as hereinafter described to produce a shale oil mixture; conducting said mixture in intimate admixture with oxygen to a cracking reactor and effecting oxidative crack. ing of the mixture; conducting the vaporous oil-containing product from said cracking reactor to a converter to contact said vaporous oilcontaining product with said spent shale which has been pretreated with a mineral oxy-acid so as to convert the oxygenated organic compounds resulting from the oxidative cracking step to the corresponding hydrocarbons; contacting the vaporous product from said converter in direct countercurrent heat exchange relationship in a preheating zone to produce said preheated oil shale and to condense a portion of said vaporous product; removing said heavy oil fraction as a condensate from an intermediate point of said preheating zone; removing the uncondensed gases and further liqueed product from said preheating zone and separating the water from said liquefied product.

l1. A method for the recovery of shale oil from oil shale which comprises: causing fresh oil shale to move upwardly through a preheating zone in direct, countercurrent heat exchange relationship with product shale oil vapors to preheat said shale and to condense a portion of said product shale oil vapors; permitting free movement of preheated oil shale from the upper section of the preheating zone to the upper section of a separate contiguous retorting zone; causing said oil shale to move downwardly through the retorting zone countercurrently toa stream of hot combustion gases and superheated steam whereby heat is supplied to said oil shale to obtain said product shale oil vapors and whereby fresh oil shale inthe preheating zone is further preheated by indirect heat exchange relationship with the oil shale in the retorting zone to produce said preheated oil shale; producing said combustion gases by maintaining through the use of oxygen a zone of combustion in the lower section of said retorting zone; producing said superheated steam by introducing water directly upon the hot spent shale from the zone of combustion at a point below the zone of combustion, whereby said hot spent shale is simultaneously cooled, and superheating the resulting steam upon upward passage of the steam to and through said combustion zone; removing cooled spent shale from the retorting zone; and removing condensed shale oil from the lower section of the preheating zone.

References Cited in the tile of this patent UNITED STATES PATENTS Number Name Date 17,781,934 Snyder Nov. 18, 1930 1,976,696 Ellis Oct. 9, 1934 2,014,212 Seguy Sept. 10, 1935 2,264,427 Asbury Dec. 2, 1941 2,317,379 Hemminger Apr. 27, 1943 2,369,523 Belchetz Feb. 13, 1945 .2,371,147 Burk Mar. 13, 1945 2,406,810 Day Sept. 3, 1946 2,489,702 Coast Nov. 29, 1949 

1. A SYSTEM FOR RECOVERY OF SHALE OIL FROM OIL SHALE COMPRISING IN COMBINATION AN UPRIGHT HEAT EXCHANGER, AN UPRIGHT RETORTING VESSEL AND A CRACKING REACTOR, SAID UPRIGHT HEAT EXCHANGER PROVIDED THEREIN WITH ELEVATING MEANS FOR ELEVATING PARTICULATE SOLID MATERIAL AND PROVIDED THEREIN WITH INTERMEDIATE COLLECTING MEANS FOR LIQUEFIED PRODUCT AND FURTHER PROVIDED WITH LIQUID AND GASEOUS COLLECTING MEANS IN THE BOTTOM THEREOF, CONDUIT MEANS CONNECTING THE UPPER ENDS OF SAID HEAT EXCHANGER AND SAID RETORT VESSEL AND ADAPTED FOR TRANSFERRING PARTICULATE SOLID MATERIAL FROM SAID HEAT EXCHANGER TO SAID RETORT VESSEL, SAID RETORT VESSEL PROVIDED WITH AN OUTLET OPENING NEAR THE UPPER END THEREOF AND FURTHER PROVIDED WITH TWO SEPARATE FEED INLETS NEAR THE BOTTOM THEREOF ONE AT A HIGHER POSITION THAN THE OTHER AND A DISCHARGE OPENING AT THE BOTTOM FOR REMOVAL OF PARTICULATE SOLID MATERIAL THEREFROM, A FIRST CONDUIT MEANS CONNECTING SAID OUTLET OPENING NEAR THE UPPER END OF SAID RETORT VESSEL WITH AN INLET OPENING AT ONE END OF SAID CRACKING REACTOR, A SECOND CONDUIT MEANS CONNECTING SAID HEAT EXCHANGER WITH AN INTERMEDIATE POINT OF SAID FIRST CONDUIT MEANS, MEANS FOR INTRODUCING OXYGEN INTO SAID FIRST CONDUIT MEANS BETWEEN SAID INTERMEDIATE POINT AND SAID CRACKING REACTOR, SAID CRACKING REACTOR PROVIDED WITH AN OUTLET OPENING AT THE OTHER END THEREOF AND CONDUIT MEANS CONNECTING SAID OUTLET OPENING OF SAID CRACKING REACTOR WITH THE UPPER SECTION OF SAID HEAT EXCHANGER.
 8. A METHOD OF RETORTING OIL SHALE WHICH COMPRISES; INTRODUCING PREHEATED OIL SHALE INTO THE UPPER SECTION OF A RETORT, CAUSING A BED OF SAID OIL SHALE TO MOVE DOWNWARD THROUGH A RETORTING ZONE IN SAID RETORT COUNTERCURRENTLY TO A STREAM OF HOT COMBUSTION GASES AND SUPERHEATED STEAM IN PROPORTIONS AND SENSIBLE HEAT CONTENT AND HAVING A TEMPERATURE SUFFICIENT TO RETORT THE OIL SHALE TO SHALE OIL AND SPENT SHALE; PRODUCING SAID COMBUSTION GASES BY MAINTAINING THROUGH THE USE OF OXYGEN AND THE SPENT SHALE FROM WHICH SHALE OIL HAS BEEN SUBSTANTIALLY VAPORIZED A ZONE OF COMBUSTION IN THE LOWER SECTION OF SAID RETORT; PRODUCING SAID SUPERHEATED STEAM BY INTRODUCING WATER DIRECTLY UPON THE HOT SPENT SHALE FROM THE ZONE OF COMBUSTION AT A POINT BELOW THE ZONE OF COMBUSTION AND SIMULTANEOUSLY COOLING SAID HOT SPENT SHALE AND SUPERHEATING SAID STEAM UPON UPWARD PASSAGE OF THE STEAM TO AND THROUGH SAID COMBUSTION ZONE; AND REMOVING THE COOLED SPENT SHALE FROM THE RETORT. 